Description of problem:
during tempest run of this api test :tempest.api.compute.servers.test_virtual_interfaces

I saw an error. verified it manually and  get same error : 
  
[stack@undercloud ~]$ nova virtual-interface-list bae94215-cda7-4307-9425-f491f2be2343 
ERROR (ClientException): Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.
<type 'exceptions.NotImplementedError'> (HTTP 500) (Request-ID: req-2dc1eff6-874c-4a7c-b731-a56a6b9796fb)
[stack@undercloud ~]$ rpm -qa |grep -i nova 
openstack-nova-conductor-12.0.2-5.el7ost.noarch
openstack-nova-compute-12.0.2-5.el7ost.noarch
openstack-nova-scheduler-12.0.2-5.el7ost.noarch
openstack-nova-api-12.0.2-5.el7ost.noarch
python-nova-12.0.2-5.el7ost.noarch
openstack-nova-cert-12.0.2-5.el7ost.noarch
openstack-nova-common-12.0.2-5.el7ost.noarch
python-novaclient-3.1.0-2.el7ost.noarch


tempest test failed : https://rhos-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/ospd_qe-8_director-puddle-rhel-7.2-virthost-1cont_1comp_1ceph-isolation-ceph_internal-ipv4-vxlan-ssl/20/testReport/tempest.api.compute.servers.test_virtual_interfaces/VirtualInterfacesTestJSON/test_list_virtual_interfaces_id_96c4e2ef_5e4d_4d7f_87f5_fed6dca18016_network_/
Version-Release number of selected component (if applicable):


How reproducible:
always 

Steps to Reproduce:
1.run tempest api test : 
tools/run-tests.sh "tempest.api.compute.servers.test_virtual_interfaces" 
2.
3.

Actual results:


Expected results:


Additional info: